Push-button keyboard for telephone instrument - has spring contact which also hold keys in off position

摘要

The keyboard assembly has a moulded base (1) with a pair of vertical guides (7,7') for each key or button (6). In the space between the guides spring loaded contacts are arranged (3,4) and are attached to leaf springs. The button (6) has a corresponding projection (13) which is a sliding fit in the recess formed by the guides (7,7'). A step (16) at the bottom edge of the projection (13) bears against the upper spring (4) when the button is depressed and pushes it into contact with the lower spring (3). The construction simplifies the keyboard assembly without any loss of key guide accuracy, and eliminates the need for separate key return springs.